Process for the production of thiophenes from alpha-methylene ketones in the single-stage process and new ortho-fused thiophenes produced by means of the process

Abstract

Described is a novel process which can be carried out as a single-stage synthesis for the production of substituted and/or b,d- ortho-fused thiophenes. Serving as starting compounds and α-methylene ketones which are reacted in an preferably alcoholic solvent with bromine whereafter the formed intermediate product after separation from the solvent is reacted directly with a sulphurising agent. Preferably under reflux conditions in a suitable solvent to form the end product. In this way also hitherto unknown ortho-fused thiophene compounds are synthesized more especially those with 5 or 9 rings condensed with one another.

I claim: 
     
       1. A process for the production of a thiophene or b.d-ortho-fused thiophene, comprising: reacting an α-methylene ketone in a polar solvent with bromine to form a 2-bromo-1-ketone,   separating the solvent out,   directly reacting the formed 2-bromo-1-ketone with a sulphurising agent in a solvent to form a reaction product, and   isolating the formed reaction product.   
     
     
       2. The process according to claim 1, wherein the α-methylene ketone is a unsubstituted or substituted aryl methyl ketone. 
     
     
       3. The process according to claim 2, wherein the aryl methyl ketone is acetophenone. 
     
     
       4. The process according to claim 1, wherein the α-methylene ketone is a unsubstituted substituted hydroaromatic 5-ring ketone, 6-ring ketone or 7-ring ketone. 
     
     
       5. The process according to claim 4, wherein the hydroaromatic ring ketone is a 1-indanone, a 1-acenaphthenone, tetrahydrobenzanthracenone or a 1-tetralone or a benzosuberone. 
     
     
       6. The process according to claim 1, wherein the α-methylene ketone is a unsubstituted or substituted hydroheteroaromatic ketone. 
     
     
       7. The process according to claim 6, wherein the hydroheteroaromatic ketone is a tetrahydrobenzothiophenone. 
     
     
       8. The process according to claim, wherein the α-methylene ketone is substituted by one or more linear or branched alkyl groups, methoxy groups, masked amino groups or carbonyl groups. 
     
     
       9. The process according to clam 1, wherein the polar solvent for the reactiobn with bromine is an alcohol, ether, glacial acetic acid, chloroform or carbon tetrachloride. 
     
     
       10. The process according to claim 9, wherein the solvent for the reaction with bromine is a low molecular weight alcohol (C 1-4 ). 
     
     
       11. The process according to claim 10, wherein methanol is used as the solvent. 
     
     
       12. The process according to claim 1, wherein a phosphorus-sulphur compound of the formula P 4  S x  is used as sulphurising agent, in which formula, x has the value 3, 5, 7, 9 or 10 and that an aromatic hydrocarbon or pyridine is used as solvent. 
     
     
       13. The process according to claim 12, wherein benzene, toluene and/or xylene is used as solvent for the reaction with the sulphurising agent,. 
     
     
       14. The process according to claim 12, wherein the molar ratio of sulphurising agent to ketone is in the range from 0 .1:1 to 1.5:1. 
     
     
       15. The process according to claim 1, wherein Lawessons reagent is used as sulphurising agent and an aromatic hydrocarbon or pyridine is used as solvent. 
     
     
       16. The process according to claim 15, wherein benzene, toluene or xylene or mixtures thereof is used as solvent for the reaction with the sulphurising agent. 
     
     
       17. The process according to claim 15, wherein the molar ratio of sulphurising agent to ketone is in the range from 0.5:1 to 1.5:1. 
     
     
       18. The process according to claim 1, wherein a phosphorus-sulphur compound of the formula P 4  S x , in which x has the value 3, 5, 7, 9 or 10, is used as sulphurising agent, in combination with Na 2  S, NaHCO 3  or Na 2  CO 3  as catalyst and a polar solvent. 
     
     
       19. The process according to claim 18, wherein the polar solvent is tetrahydrofuran, diethylene glycol dimethyl ether or ether. 
     
     
       20. The process according to claim 1, wherein silicon disulphide or boron sulphide (B 2  S 3 ) is used as sulphurising agent and chloroform or an aromatic hydrocarbon is used as solvent. 
     
     
       21. The process according to claim 1, wherein 0,0-diethyl dithiophosphoric acid is used as sulphurising agent. 
     
     
       22. The process according to claim 1, wherein the reaction with the sulphurising agent is carried out under reflux conditions at temperatures up to 200° C.